1. Field of the Invention
The invention relates to a system for remote control of a computer system, and in particular to real-time remote diagnostic computer systems to monitor, update, and repair remotely located modems. This invention further relates to a method of monitoring, updating, and repairing remotely located modems.
2. Description of Related Art
Computers traditionally use modems for transmitting and receiving data over telephone lines. One type of modem, a host signal processing (HSP) modem, uses a central processing unit (CPU) in a host computer to perform processing tasks that are more commonly performed by modem hardware such as a digital signal processor in a conventional modem. For example, a conventional modem receives data from a host computer, uses hardware in the modem to convert the data to an analog signal in compliance with a communication protocol, and transmits the analog signal to a remote device. The conventional modem also receives an analog signal from the remote device, uses hardware in the modem to extract data from the analog signal, and passes the data to the host computer.
In an HSP modem, also known as a software modem, the host computer executes software that performs many of the conversions performed by a digital signal processor or other hardware in a conventional modem. Hardware in the HSP modem performs simple analog-to-digital and digital-to-analog conversions such as converting a received analog communication signal to a series of digital samples that represent amplitudes of the received signal. The host computer executes software that interprets the samples according to a communication protocol and derives the received data from the samples. The host computer also generates a series of output samples that represent amplitudes of a transmitted communication signal in compliance with the protocol, and hardware of the HSP modem converts the output samples into the transmitted signal. When compared to conventional modems, HSP modems have less complex (and less expensive) hardware because with HSP modems, the host computer performs many of the tasks performed by hardware in conventional modems.
An additional benefit of HSP modems is that a user can modify or upgrade the modem by simply installing updated HSP software onto the host computer. This eliminates the need for costly hardware upgrades and enables the user to modify the performance of the HSP modem relatively frequently and economically.
The analog signals sent from modems are typically sent over conventional telephone lines. The characteristics of the carrier telephone lines can vary significantly from location to location. The variation in signal-carrying characteristics and quality becomes particularly acute when dealing with telephone lines overseas.
Testing and modifying modems, both conventional hardware modems and HSP modems, has heretofore required that an operator or tester be in the area where modem performance is being tested on local phone lines. The necessity of having an operator of the computer system and modem being tested often requires a great deal of time and expense, particularly when the computer system is located inconveniently, such as at a remote overseas site. For vendors, diagnosing and repairing complex hardware and software problems on a customer's installed computer system typically requires that a support technician travel to the customer's location to work on the computer system on-site. This also involves a great deal of time and travel expense, particularly in the case of systems installed overseas. Similar types of expenses are incurred when a modem manufacturer wishes to test the performance of a particular modem over the local telephone lines at a remote site.